首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   281篇
  免费   12篇
耳鼻咽喉   1篇
儿科学   17篇
妇产科学   14篇
基础医学   46篇
口腔科学   28篇
临床医学   21篇
内科学   59篇
皮肤病学   3篇
神经病学   19篇
特种医学   5篇
外科学   27篇
预防医学   32篇
眼科学   1篇
药学   11篇
肿瘤学   9篇
  2022年   5篇
  2021年   5篇
  2020年   6篇
  2019年   3篇
  2018年   11篇
  2017年   2篇
  2016年   7篇
  2015年   6篇
  2014年   8篇
  2013年   12篇
  2012年   19篇
  2011年   18篇
  2010年   7篇
  2009年   14篇
  2008年   14篇
  2007年   17篇
  2006年   19篇
  2005年   16篇
  2004年   12篇
  2003年   12篇
  2002年   17篇
  2001年   7篇
  2000年   10篇
  1999年   10篇
  1998年   6篇
  1997年   3篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1992年   2篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
  1985年   2篇
  1984年   3篇
  1983年   1篇
  1982年   1篇
  1979年   2篇
排序方式: 共有293条查询结果,搜索用时 15 毫秒
91.
92.
Aim: To determine whether repeated infancy-onset lifestyle counselling alters parental smoking and children's exposure to tobacco smoke. Methods: In 1990, 1062 healthy infants were recruited to a randomized, ongoing atherosclerosis prevention trial (STRIP). Intervention families received at least twice a year individualized nutrition and lifestyle counselling. By 1999, 652 8-y-old children continued participation. Exposure to tobacco smoke was evaluated using serum cotinine concentration. Parents' smoking was also assessed using questionnaires and interviews. Results: Parents' smoking decreased during the study similarly in the intervention and control groups. Of the 8-y-old children, 46% had detectable serum cotinine concentration, suggesting exposure to tobacco smoke during the past few days. All children were non-smokers. Serum cotinine concentrations did not differ between the intervention and control children. Children's cotinine values were highest in the families where either father or both parents were smokers.

Conclusion: Participation in the atherosclerosis prevention trial slightly decreased smoking among the intervention and control parents. However, counselling led to no differences in parental smoking between the two groups, or in exposure of the intervention and control children to tobacco smoke. This study suggests that more detailed and targeted intervention is required to achieve a significant effect on children's tobacco smoke exposure.  相似文献   
93.
94.
Biochemical and molecular genetic studies have recently suggested that mutations in the gene coding for fibrillin on chromosome 15 result in Marfan syndrome. To our knowledge, only one mutation in the fibrillin gene has been published. Here we report the results of screening 20 unrelated MFS patients for mutations in fibrillin cDNA by the single-strand conformation polymorphism technique. We found two mutations, both of which appear in the heterozygote form and code for a shortened fibrillin polypeptide. The first mutation is a large in-frame deletion of 366 bases of the fibrillin mRNA, shown to result in a truncated but secreted polypeptide found in the fibroblast culture of the patient. The second mutation is a G-to-A transition resulting in the substitution of a stop codon for a tryptophan codon and thus predicting the premature termination of the polypeptide chain. We screened 60 other, unrelated MFS patients for these mutations as well as for the previously reported mutation (arginine-239 to proline) and found none of the three mutations in any of these patients. These data suggest that most MFS families carry their own distinct mutation.  相似文献   
95.
We calculated morphometrically the amount of antral gastrin-producing (G) cells and body parietal and chief cells in gastric biopsy specimens from 30 undialysed patients with chronic renal failure (CRF) and from sex- and age-matched controls. The CRF patients had raised fasting serum gastrin levels, whereas these were normal in the controls (mean, 290 +/- 283 (+/- SD) ng/l (n = 27) versus 33 +/- 36 (n = 30)). Serum gastrin values of the patients and controls correlated positively with G-cell density (r = 0.501, n = 36, p = 0.002), as did the maximal acid output of the CRF patients with parietal cell density (r = 0.617, n = 14, p = 0.019). In CRF patients the densities of G, parietal, and chief cells were higher than those in the controls (G cells, 351 +/- 151 (+/- SD) cells/mm2, n = 21 versus 211 +/- 90, n = 16, p = 0.002; parietal cells, 299 +/- 94, n = 15 versus 224 +/- 72, n = 14, p = 0.025; chief cells, 886 +/- 346, n = 15 versus 743 +/- 182, n = 14, p = 0.181). The results agree with previous findings indicating that hyposecretion of gastric acid in CRF does not derive from decreased capacity for acid secretion but rather from the inhibition of acid output. Increased parietal cell density in CRF patients gives cause to suspect that the maximum acid output might even in raised, possibly depending on the permanent hypergastrinaemic state with its trophic influence on the gastric body mucosa.  相似文献   
96.
OBJECTIVES: To review, on a genome-wide scale, a linkage result obtained in an earlier candidate gene analysis in this same study sample, and to look for other possible contributing genetic loci predisposing to hypertension in this population. DESIGN: An affected sibpair linkage study with highly polymorphic genetic markers spanning the genome at an average intermarker density of 10 cM. PARTICIPANTS: A total of 47 families with two affected siblings (mostly dizygotic twins) and all available additional family members from the genetic isolate of Finland. The families were identified through the Finnish Twin Cohort Study, the total number of this follow-up cohort being 13,888. The study sample was selected on the basis of early-onset hypertension with minimal presence of other phenotypic risk factors such as obesity. RESULTS: The AT1 locus stood out as the most significant locus in this population (maximum likelihood score 4.04). Some evidence for linkage was also detected with markers on chromosomes 2q (maximum likelihood score 2.96), 22q (2.07), and Xp (2.41). CONCLUSIONS: Our results establish the role of the AT1 locus, on a genome-wide scale, as a major contributing locus to essential hypertension in this study sample.  相似文献   
97.

Introduction

This prospective magnetic resonance imaging (MRI) study in chronic low-back pain (CLBP) patients evaluated the natural course of degenerative lumbar spine changes in relation to Modic 1 type changes (M1) within 1 year.

Materials and methods

From 3,811 consecutive CLBP patients referred to lumbar spine MRI 54 patients with a large M1 were selected using strict exclusion criteria to exclude specific back disorders. Follow-up MRI was obtained within 11–18 months.

Results

At baseline M1 was associated with an adjacent endplate lesion in 96% of the cases. In follow-up, an unstable M1 was associated both with an increase of endplate lesions, decrease of disc height and change in disc signal intensity, most found at L4/5 or L5/S1. In disc spaces without M1, progression of degenerative changes was rare.

Conclusion

Endplate deformation, decreasing disc height and change of disc signal intensity appear essential features of accelerated degenerative process associated with M1.  相似文献   
98.
99.

Purpose

To study the changes in the immunological status in 2 children with cartilage hair hypoplasia (CHH).

Methods

A 4–6 year immunological follow-up from infancy.

Results

In infancy the children presented a combined T cell and B cell immunodeficiency which partly resolved in time. Mitogen-induced T cell proliferation values fluctuated but lymphopenia has remained constant. Both patients had no recent thymic emigrants (TREC). Both children have suffered from a prolonged viral infection. Hypogammaglobulinemia normalized during the first years of life but both children have a specific antibody deficiency (SAD).

Conclusions

The changes in the immunological status in CHH patients emphasize the importance of a regular follow-up. SAD should be searched for in CHH. The absence of TRECs supports combined immunodeficiency and possible need of hematopoietic stem cell transplantion.  相似文献   
100.
Background

Intra-articular venous malformations of the knee are an uncommon cause of unilateral knee pain in children. Timely diagnosis is important because lesions with intrasynovial involvement can lead to joint space hemorrhage and secondary cartilage damage.

Objective

To describe our tertiary center’s experience of diagnostics and typical magnetic resonance imaging (MRI) findings.

Materials and methods

A retrospective review of all patients ≤16 years of age managed for intra-articular venous malformations of the knee at our institution between 2002 and 2018.

Results

Of 14 patients (8 male), the mean age at presentation was 6 years (range: 0–14 years). The most common clinical findings were unilateral knee pain (93%), joint swelling (79%), quadriceps atrophy (50%) and a limited range of motion (29%). Cutaneous manifestations were present in four patients (29%). Contrast-enhanced MRI was available in all cases. After initial MRI, a vascular anomaly etiology had been identified in 11 cases (79%), and correctly reported as a venous malformation in 6 (55%). Three patients received entirely different diagnoses (arthritis, tumor or pigmented villonodular synovitis). Three of seven patients with intrasynovial lesions had established chondropathy at diagnosis. Two patients with lesions of the suprapatellar fat pad had intrasynovial involvement that was not visualised on MRI.

Conclusion

Although MRI usually permits the diagnosis, clinical awareness of these lesions is important for optimal imaging, accurate interpretation and timely diagnosis. Involvement of the intrasynovial cavity carries a risk of hemarthrosis and progressive chondropathy that may be underestimated by MRI.

  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号